$(document).ready(function() {

  var canvas = document.getElementById('canvas'),
    ctx = canvas.getContext('2d'),
    w = canvas.width = window.innerWidth,
    h = canvas.height = window.innerHeight,

    hue = 235,
    stars = [],
    count = 0,
    maxStars = 1300; //星星数量
  $(window).resize(function() {
    w = canvas.width = window.innerWidth;
    h = canvas.height = window.innerHeight;
    for (var i = 1; i < maxStars + 1; i++) {
      stars[i].orbitRadius = random(maxOrbit(w, h));
      stars[i].radius = random(60, stars[i].orbitRadius) / 8;
    }
  })
  var canvas2 = document.createElement('canvas'),
    ctx2 = canvas2.getContext('2d');
  canvas2.width = 100;
  canvas2.height = 100;
  var half = canvas2.width / 2,
    gradient2 = ctx2.createRadialGradient(half, half, 0, half, half, half);
  gradient2.addColorStop(0.025, '#CCC');
  gradient2.addColorStop(0.1, 'hsl(' + hue + ', 61%, 33%)');
  // gradient2.addColorStop(0.25, 'hsl(' + hue + ', 64%, 6%)');
  gradient2.addColorStop(1, 'transparent');

  ctx2.fillStyle = gradient2;
  ctx2.beginPath();
  ctx2.arc(half, half, half, 0, Math.PI * 2);
  ctx2.fill();

  // End cache
  function random(min, max) {
    if (arguments.length < 2) {
      max = min;
      min = 0;
    }

    if (min > max) {
      var hold = max;
      max = min;
      min = hold;
    }

    return Math.floor(Math.random() * (max - min + 1)) + min;
  }

  function maxOrbit(x, y) {
    var max = Math.max(x, y),
      diameter = Math.round(Math.sqrt(max * max + max * max));
    return diameter / 2;
    //星星移动范围，值越大范围越小，
  }

  var Star = function() {

      this.orbitRadius = random(maxOrbit(w, h));
      this.radius = random(60, this.orbitRadius) / 8;
      //星星大小
      this.orbitX = w / 2;
      this.orbitY = h / 2;
      this.timePassed = random(0, maxStars);
      this.speed = random(this.orbitRadius) / 500000;
      //星星移动速度
      this.alpha = random(2, 10) / 10;

      count++;
      stars[count] = this;
    }

  Star.prototype.draw = function() {
    var x = Math.sin(this.timePassed) * this.orbitRadius + this.orbitX,
      y = Math.cos(this.timePassed) * this.orbitRadius + this.orbitY,
      twinkle = random(10);

    if (twinkle === 1 && this.alpha > 0) {
      this.alpha -= 0.05;
    } else if (twinkle === 2 && this.alpha < 1) {
      this.alpha += 0.05;
    }

    ctx.globalAlpha = this.alpha;
    ctx.drawImage(canvas2, x - this.radius / 2, y - this.radius / 2, this.radius, this.radius);
    this.timePassed += this.speed;
  }

  for (var i = 0; i < maxStars; i++) {
    new Star();
  }

  function animation() {
    ctx.globalCompositeOperation = 'source-over';
    ctx.globalAlpha = 0.5; //尾巴
    ctx.fillStyle = 'hsla(' + hue + ', 64%, 6%, 2)';
    ctx.clearRect(0, 0, w, h)

    ctx.globalCompositeOperation = 'lighter';
    for (var i = 1, l = stars.length; i < l; i++) {
      stars[i].draw();
    };

    window.requestAnimationFrame(animation);
  }

  animation();

  // function strToJson(str){
  //   var json = eval('(' + str + ')');
  //   return json;
  // }
  // $('.l-btn').click(function(){
  //   var userData;
  //   var userName = $('.userico input').val();
  //   var userPwd = $('.pwdico input').val();
  //   if(userName && userPwd){
  //       $.action("../../../cMapService/loginAction.do?method=login","userid="+ userName +"&userpwd="+ userPwd +"",function(msg){
  //       	jQuery.cookie("userid",msg,{path:'/'});
  //       	jQuery.cookie("user",userName,{path:'/'});
  //       	window.location.href = "../main1/index.jsp";
  //       },"text",false,false);
  //   }else{
  //       alert('用户名和密码不能为空');
  //   }
  //   return false
  // })

  // jQuery("#userid").on({
	 //  keydown:function(){
		//   if(event.keyCode == 13) {
		// 	  $('.l-btn').click();
		//   }
	 //  }
  // });
  // jQuery("#userpwd").on({
	 //  keydown:function(){
		//   if(event.keyCode == 13) {
		// 	  $('.l-btn').click();
		//   }
	 //  }
  // });
  

});